The present invention relates to an image capturing unit that is adapted to be built in a tip portion of an electronic endoscope.
Generally, an image capturing unit of an electronic endoscope including a solid-state image capturing element is provided with bonding wires that conduct electricity to a conductive material arranged behind the solid-state image capturing element. The bonding wires are loosely bent in a front space of the solid-state image capturing element and arranged to extend from edges of an image capturing area outwardly. Such an image capturing unit is generally further provided with a transparent cover glass to protect the solid-state image capturing element, which is fixed to a frame of the image capturing unit. Examples of such an image capturing unit are disclosed in Japanese Patent Provisional Publication Nos. 2003-100920 and HEI 10-74865.
As an inserted portion of a tip of the endoscope is adapted to be inserted into live bodies, the image capturing unit of the endoscope is required to be downsized by tenths of a millimeter to a minimum extent.
In the image capturing units disclosed in the above-referenced publications, however, outlines of the cover glasses are formed to be greater than an area wherein the bonding wires extend, and the cover glasses are arranged to be substantially spaced from the solid-state image capturing element so that the cover glasses do not become in contact with the bonding wires, as the bonding wires may be deteriorated by the contact.
With this structure, downsizing of an image capturing unit for the electronic endoscope is thus limited and it is difficult to configure a diameter of the tip portion to be considerably small. In such a case, a length of a solid portion of the inserted portion tends to be greater, and thus, fine movements of the inserted portion are restricted. As the movements of the inserted portion are restricted, observation capability of the endoscope may be deteriorated. Further, functionalities of an objective optical system of the endoscope, such as a zooming function, may be prevented from being improved.